DEVICE FOR TESTING AT LEAST ONE QUALITY PARAMETER OF A FLUID

Abstract

A device tests at least one quality parameter of a fluid in fluid apparatuses, e.g., working cylinders (10), hydraulic accumulators, valves, filter housing, pressure tubes, which at least temporarily accommodates given fluid volume in at least one fluid chamber (12,14). The fluid volume is stored in a storage unit (16) with the aid of a control mechanism (16) after being discharged from the fluid apparatus in order to be redirected from there into a measuring element (22, 24) to verify the respective quality parameter of the fluid. The inventive device makes is possible to specifically obtain a statement about the operability of the respective fluid apparatus within a very short period of time.

Full Text

The invention relates to a device for testing at least one quality parameter of

a fluid in fluid devices such as working cylinders, hydraulic accumulators,

valves,
filter housings, flexible pressure tubing, etc.
Subsequently published DE 102 47 353 discloses a process for reducing the flow
dependence of measuring instruments for determination of impurities as
indication of the quality of a fluid, especially solid impurities such as

particles in
fluids, by means of a particle count sensor operating in particular on the

basis of
the light blocking principle and mounted in a measuring cell of the measuring
device, which has a specifiable input cross-section for the flow of fluid, the
sensor generating a light beam cross-sectional area over which the flow of

fluid
is conducted for detection of an impurity. Particle count sensors operating on

the
light blocking principle determine the relative proportion of the light beam

cross-
sectional area (perpendicular to the optical axis) which is covered by

projection
of a pollutant particle in this plane.
DE 198 60 169 Al discloses a process for qualitative determination of small
amounts of water in multicomponent systems in the liquid state of aggregation,
oil in particular, the process being characterized by repetition of the

following
process steps several times:

incomplete extraction of moisture from the multicomponent system by
means of a carrier gas;
quantitative determination of the amount of moisture extracted by
measurement of the relative humidity in the carrier gas, the carrier gas
volume, and the temperature; and
conversion to the amount of moisture of the multicomponent system after
determination of the mass of the multicomponent system and the
saturation vapor density in the carrier gas.
The disclosed process and device provide the possibility of measuring the
absolute saturation concentration of moisture in fluids such as hydraulic oil,

the
parameter determination in question in turn permitting formulation of a
statement regarding the quality of the oil.
DE 101 52 777 Al discloses a device for determination of the quality of a
medium, a lubricant and/or cutting oil in particular, having several sensors

which
generate an electric output signal as a function of the respective

sensor-specific
input quantity, one sensor being a temperature sensor which generates an
output signal which is a function in essence exclusively of the temperature of

the
medium and is essentially independent of the quality of the medium, and at

least
one other sensor generating an output signal as a function both of the quality

of
the medium (fluid) and of the temperature of the medium. The sensors in
question are in the disclosed solution mounted on a common substrate
immersible in the fluid, so that the measuring device disclosed is mounted in a
very small structural space.
The disclosed measuring devices and processes indicated in the foregoing make
available a very good set of instruments for determination of quality

parameters
for fluids, including media in the form of a gas and/or paste. The respective
measuring devices may also be supplemented by chemical analysis processes,
for example, in order to arrive at determinations regarding free radicals in a
hydraulic oil, temperature, viscosity, pH value, electric conductivity, etc.

Such
devices entail a prolonged measurement or determination period depending on
the measuring process employed, along with the associated measurement device
and depending on the quality parameters of the fluid to be determined. Out of
consideration of reasons of process accuracy, length of the measurement period,
and the validity of the test result it has been found to be advisable to use

such
quality measurement processes directly on test stands where the operation of
fluid devices such as hydraulic assemblies, valves, filter housings, flexible
pressure tubing, etc., may be tested. Use of the respective operating fluid is
necessary, on location, in order to verify the quality of the fluid thus used

by
means of the measuring device, if possible simultaneously with testing of the
assembly. In this way determination is made of the suitability of the

respective
fluid device for subsequent operation in order, in turn, to obtain a broader
indication of the quality of the preceding production steps with respect to the
fluid device (assembly) which has been or is to be tested.
On the basis of these considerations, the object of the present invention
accordingly is to create a device meeting the requirement as outlined. The

object
as thus defined is attained by means of a device having the characteristics
specified in claim 1 in its entirety.
The device claimed for the invention for testing at least one quality parameter

of
a fluid of fluid devices is characterized in that at least occasionally a

specified
volume of fluid is received into at least one fluid space of a particular fluid

device
and, after leaving the fluid device, may be stored in a storage device by means
of a control device in order subsequently to be fed further to a measuring

device
for determination of the respective quality parameter of the fluid to be
determined.
If a fluid device has been produced, for example, in the form of working
cylinders, hydraulic accumulators, valves, filter housings, flexible pressure

tubing,
etc., and is placed on a testing stand, the functional testing generally has

been
preceded by a plurality of production steps involving machining to some extent,
something which usually results in fouling of the fluid spaces of the

respective
fluid device. Fouling occurs even if no machining has been carried out, either

in
the form of dust or in the form of operating media such as corrosion protection
means, lubricants, other hydraulic media, etc. If delivery is then made to
customers, after appropriate functional testing, in which the operating fluid

is
admitted to the respective fluid device, fouling matter remaining in the fluid
spaces could impede subsequent operation and result both in failure of the
respective fluid device and failure of all-hydraulic unit, even if such units

are
additionally protected by filter devices or the like.
It has been found in practical applications that the danger in question may be
reduced if on the test stand the fluid medium is applied to the fluid spaces of

the
fluid device involved several times in a sort of scavenging process and the

spaces
are then emptied of the fluid medium in order to obtain a yield at least of

fouling
particles. However, even if a very high number of scavenging processes are
carried out the possibility cannot be excluded that in a special case fouling
material may remain in the fluid space and then result in the adverse effects
indicated in the hydraulic circuit in subsequent operation of the fluid device.

In
order to prevent such occurrence, it is claimed for the invention that, after

the
scavenging cycle has been completed, the last amount of fluid introduced is
subjected to thorough testing by the appropriate measuring device. If the fluid
space is small because of the geometric dimensions of the respective fluid
device, the volume of fluid involved may be taken directly to the measurement
device for online measurement if the amount of fluid present in the fluid space

is
sufficient for such online measurement; otherwise the amount of fluid required
for reliable online measurement may be collected and made available by the
device claimed for the invention. With fluid devices of large dimensions in
particular, however, the fluid volumes of the fluid spaces are also large, so

that
with the online measurement process as outlined a very lengthy measurement
period elapses before the entire volume of fluid is tested, with the result

that the
test stand continues to be occupied and may not be used for testing of another
fluid device to be introduced into the test stand. The invention is introduced

at
this point and takes from the large amount of fluid the amount required for
online measurement. The device claimed for the invention is especially well
suited for applications in which only brief testing or measurement periods are
available. The measurement stand itself accordingly assumes very high
measurement cycles and amounts of fluid which depart from the optimum
measurement volume, for example, because the amounts of fluid employed are
very small or very large.
The device claimed for the invention now makes it possible for the amount of
fluid of the last scavenging cycle to be introduced by means of a control

device
into a storage device and from the latter the fluid to be tested may be moved

on
to the measuring device, the control device simultaneously permitting change of
the fluid device to be tested on the test stand. Replacement of the fluid

device
may accordingly be undertaken while the measurement (testing) proper for the
preceding fluid device is still in progress. Hence, the device claimed for the
invention is especially well suited for quality parameter checking in fluid

devices
if large volumes of fluid are to be tested and/or only brief measurement

periods
are available for this or other reasons. Because of the intelligent

configuration of
the control device, preferably as microprocessor equipment, it is possible to

use
fluid devices having fluid spaces of small dimensions to conduct online testing

or
testing after a prescribed delay period, it being possible to use the

measurement
period in question to effect the desired replacement on the test stand. The
device claimed for the invention accordingly helps in lowering the expenditure

of
time and costs and, because of the solution applied, may be suitably employed

in
a multiplicity of embodiments.
By preference the storage device in question consists of a working cylinder, in
particular one in the form of a pneumatic cylinder which may be connected on
the piston side by way of a feed line so as to conduct fluid to the associated

fluid
space of the fluid device by means of the control device, the measurement
device being mounted in the direction of flow of the fluid beyond the working
cylinder in a discharge line. If the volume of the storage unit is sufficiently

large,
if desired several quantities of fluid may be stored for several consecutive

rinse
cycles and then recalled for the overall measurement. This permits a

regarding
the quality of the fluid device produced.
The device claimed for the invention may be used in particular to obtain a
reliable indication of the fouling status of the fluid to be tested and thus of

the
fluid device. Should such be desired, in addition to determination of the

number
of (fouling) particles, depending on the measurement device employed
indications may also be obtained of the size, type, and speed of the particles
present in the fluid to be tested. The respective quality parameter test may be
further supplemented by other values such as viscosity, temperature, free
radicals, pH values, electric conductivity of the fluid to be tested, etc.
Additional advantageous embodiments are presented in the other dependent
claims.
The device claimed for the invention will be described in what follows on the
basis of an exemplary embodiment with reference to the accompanying drawing,
in which there is presented in the sole drawing, in diagrammatic form not drawn
to scale, the structure of the device claimed for the invention for testing a
hydraulic working cylinder after completion of a specifiable number of testing
and scavenging cycles, the hydraulic device carrying out the scavenging cycle
being omitted for the sake of greater simplicity of presentation.
The device shown as a whole in the figure serves the purpose of testing at

least
one quality parameter of a fluid in fluid devices, such as one in the form of a
hydraulic working cylinder 10. A fluid device such as this at least

occasionally
receives a specified volume of fluid in at least one fluid space. In the

present
situation the hydraulic working cylinder 10 has a fluid space 12 on the rod

side
and a fluid space 14 on the piston side. The respective volume of fluid, after
leaving the fluid device, in this instance in the form of the hydraulic working
cylinder 10, may be stored by means of a control device identified as a whole

by
16 in a storage device. There are associated with the fluid space 12 the

storage
device 18 and with the fluid space 14 on the piston side another storage device
20, which is essentially the same in design as the first storage device 18. The
volume of fluid may be moved from the storage device 18, 20 to an associated
measurement device 22, 24, which serves to determine the respective quality
parameter of the fluid. The measurement devices in question are essentially
equivalent to each other.
A measurement device 22, 24 such as is described in DE 102 47 353 may be
employed as the respective measurement device 22, 24. The measurement
device as described carries out a process for reducing the dependence of the
respective measurement devices on flow for determination of impurities,
especially fouling by solids such as particles in fluids, by means of a

particle
count sensor, especially one operating on the light-blocking principle and
mounted in a measuring cell of the measurement device having a specified inlet
cross-section for the flow of fluid, the sensor generating a light beam cross-
sectional area over which the flow of fluid is conducted for detection of the
impurity in the flow of fluid, the light beam cross-sectional area selected for

the
direction of flow of the fluid being greater than such area transverse to the

point
of entry of the impurity into the light beam cross-sectional area.
There is thus obtained a light beam cross-sectional area, preferably generated

by
a conventional laser, of the particle count sensor which does not illuminate

the
complete cross-sectional area of the measuring cell, but on the other hand is
distinctly of greater extent in the direction of flow, with the result that

even
markedly small (fouling) particles, such as ones of a size of 2 |am, can be
immediately detected without increase in the cost of measurement with the
equipment mounted downstream. An evaluation process suitable for such a
particle counter is described in detail in DE 197 35 066 Cl and thus will not

be
dealt with at greater length here. However, the device disclosed makes it
possible reliably to detect even the smallest particle. The possibility also

exists of
detecting air bubbles in the flow of fluid in order to arrive at permissible
statements concerning the quality of the fluid which may also result from
different particle geometries.
The respective storage device 16, 18 consists of a working cylinder, in

particular
one in the form of a pneumatic cylinder of conventional design, which may be
connected on the piston side by way of a feed line 26 so as to conduct fluid to
the fluid space 12,14 of the fluid device associated with it by means of the
control device 16, the respective measurement device 22, 24 being mounted in
the direction of flow of the fluid downstream from the pneumatic working
cylinder in a discharge line 28. This discharge line 28 extends from the
measurement device 22, 24 by way of an adjustable choke 30 to the tank side T
of the device.
The working cylinder of the two storage devices 18, 20 has a piston rod 32 with
a through fluid duct (not shown) which discharges on one side into the
respective piston space 34 of the working cylinder and on its other side into a
connecting line 36, which in turn may be blocked by the control device 16. As

an
extension of the connecting line 36 it discharges on the tank side T. The rod

side
38 of the respective working cylinder is connected to a compressed gas source
40, in particular one in the form of a compressed air or nitrogen source, this
source providing an operating pressure of several bar, such as 6 bar. In

addition,
the movement of displacement of the piston 42 is monitored by a monitoring
device 44 as part of the control device 16 with end position switches.
The control device 16 has switching valves, in particular ones in the form of

2/2-
way switching valves 46, 48. The switching valves 46, 48 are shown in the

figure
in their output blocking position; when in their other switching position,

after
they have been operated, they clear the path for the fluid. These switching
valves 46 and 48 clear or close the fluid conducting path for the feed line 26
and/or the connecting line 36. The control device 16 uses the output signals of
the monitoring device 44 in the form of the four end-position switches shown in
the figure to operate the switching valves 46, 48. A pressure control valve 50

is
connected to the respective feed line 26 to the pneumatic working cylinder,
between the latter and the associated switching valve 46 of the control device
16. This pressure control valve 50 in turn leads to the tank side T.
For the sake of better understanding the device claimed for the invention will
now be described on the basis of a practical application. The hydraulic working
cylinder 10 shown in the figure comes from the factory and undergoes thorough
functional testing on a test stand not shown. Since machining processes are

also
involved in the production of such hydraulic working cylinders, it is to be
expected that there may be fouling material in the fluid spaces 12, 14 which

may
also derive from residue of cooling lubricants or the like. Before the device

is
employed in a practical application the hydraulic working cylinder 10 is
scavenged, that is, a fluid is alternately introduced into and removed from the
fluid spaces 12, 14, this serving the purpose of eliminating fouling material

from
these fluid spaces. Once such a scavenging cycle has been completed, first
thorough testing is effected by the associated measurement device with the
piston in the fluid space 12 retracted on the rod side. For this purpose, the
control device 16 opens the switching valve 46 and fluid flows over the feed

line
26 into the first storage device 18.
If the switching valve 48 remains closed, the quantity of fluid introduced into

the
feed line 26 may serve the purpose of scavenging both the valve 46 and the
measurement device 22, along with the piston space 34 of the storage device
18. If the switching valve 48 is closed, fluid is forced under pressure into

the
piston space 34, the piston rising to an upper end position which is checked by
the monitoring device 44. The fluid now present in the piston space 34 is then

to
be delivered to the associated measurement device 22 for the examination for
the presence of particles already described. If, surprisingly, high pressures

occur,
the proper state of the system is secured by the pressure control valve 50,

which
to this extent performs a safety function. The control device 16 now closes the
switching valve 46 and, as a result of actuation of the compressed gas source
40, pressurized gas reaches the rod side of the pneumatic cylinder and the
piston 42 moves downward as viewed in the line of sight to the figure, the

lower
end position being monitored by way of the associated end position switch of

the
monitoring device 44.
The fluid displaced by the piston then moves into the measurement device 22 by
way of the drain line 28 for the particle count indicated and thence to the

tank
side T by way of the adjustable choke 30. The measurement cycle proceeds in a
similar manner as soon as the amount of fluid in the piston fluid space 14 has
been displaced in the direction of the other storage device 20 by return of the
piston of the hydraulic working cylinder 10. If the two switching valves 46 are
then in their blocking position illustrated in the figure, during the particle
measurement itself by the measurement devices 22, 24 the working cylinder 10
which has been present in the test stand up to this point is replaced by a new
one, the measurement result for the preceding working cylinder tested by the
measurement devices 22, 24 also being present on completion of the
replacement. In this way the testing cycle, along with the testing device, is

not
harmed and very reliable test results are obtained in this instance by the

device
indicated.
Nor is it necessary to test each working cylinder. Hence, for example, only

some
of the working cylinders deriving from a processing series need be tested, by
conduct of statistical evaluation processes. The measuring device used for the
purpose is suitable in particular for fluid devices, such as large hydraulic

working
cylinders 10 having fluid spaces 12, 14 with large volumes. As a rule, the
possibility also exists of introducing several scavenging amounts in succession
into the respective storage devices, as a function of the size of the hydraulic
working cylinder 10, and then later of determining their quality by

measurement.
Consequently, the device claimed for the invention is especially well suited

for
large volume flows and for measurement periods available only for a short time.
If the hydraulic device is of small dimensions, and so the fluid spaces 12, 14

of a
hydraulic working cylinder 10, for example, are of low volume, the storage
device 18, 20 is also of assistance, so that measurement with the measurement
device 22, 24 may be effected online during a process of introduction and
removal of a cylinder. In this instance the respective switching valve 46 in

the
feed lines 26 is to be actuated. In the respective online measurement process
with low volumes of fluid, the piston 42 of the respective storage device 18,

20
moves to its respective associated position; this may be suitably effected by

way
of the control device.
The device claimed for the invention need not be restricted to hydraulic

working
cylinders; as a rule, it is suitable for use with fluid devices of any form

into which
a specifiable quantity or volume of fluid is introduced periodically.

tubing,
etc., are also conceivable. Nor need measurement be restricted to particle
evaluation: depending on the particular measurement device employed, other
data may be obtained, such as free radicals in oil, pH values, electric
conductivity, consistency, viscosity, etc.
WE CLAIM:
1. A device for testing at least one quality parameter of a fluid in a fluid
device (10) at least periodically receiving a specified volume of fluid into at

least
one fluid space (12,14) comprising:
a storage device (18,20) receiving and storing a volume of the fluid from
the fluid device (10), and being a working cylinder having a piston side
connected to the fluid (12, 14) by a feed line (26) and having a piston (42)
movable therein;
a control device (16) being in fluid communication with said storage
device (18, 20) via said feed line (26) controlling flow of the fluid from the

fluid
device (10) to said storage device;
a measurement device (22,24) being in fluid communication with and
downstream of said storage device via a drain line (28) and being capable of
determining a quality parameter of the fluid characterized by comprising:
an actuating device (40) connected to a rod side (32) of said working
cylinder (10) for moving said piston (42) in said working cylinder (10); and
a monitoring device (44) operatively coupled to and indicating positions of
said piston (42) in said cylinder.
2. A device as claimed in claim 1 wherein said monitoring device (44)
indicates end positions of said piston in said working cylinder (10).
3. A device as claimed in claim 1 wherein said actuating device (40)
comprises a source of compressed gas.
4. A device as claimed in claim 3 wherein said source (40) comprises a
compressed air nitrogen source.
5. A device as claimed in claim 1 wherein said actuator (40) comprises one
of the group consisting of an electrically and/or hydraulically operated supply
source and a compressed gas source.
6. A device as claimed in claim 1 wherein said working cylinder (10)
comprises a pneumatic cylinder.
7. A device as claimed in claim 1 wherein the fluid comprises one of the
group consisting of working cylinders, hydraulic accumulators, valves, filter
housings and flexible pressure tubing.
8. A device as claimed in claim 1 wherein said working cylinder comprises a
piston rod (32) with a through fluid conducting passage discharging on one side
into a piston space (34) of said working cylinder (10) and on another side a
connecting line (36) blocked by said control device (16).
9. A device as claimed in claim 8 wherein said control device (16) comprises
switching valves (46, 48) located in and clearing and blocking said feed line

(26)
and said connecting line; and
said control device (16) is connected to said monitoring device (44) to
receive output signal signals from said monitoring device to actuate said

switch
valves (46, 48) in response to said output signals.
10. A device as claimed in claim 9 wherein a pressure control (50) is
connected to said feed line (26) between said working cylinder and the
respective switching valve (46, 48) of said control device (16).
11. A device as claimed in claim 1 wherein a second storage device (20) and a
second measurement device (24) are in fluid communication with a second fluid
space (14) of the fluid device (10).
12. A device as claimed in claim 1 wherein said measurement device (22, 24)
determines at least one of particle size, particle number, particle speed and
particle type present in the fluid, and of viscosity, aging, temperature, pH

value
and electric conductivity of the fluid.
13. A device as claimed in claim 12 wherein the fluid device (10) is a first
hydraulic cylinder having a piston side and a rod side connectable to said
working cylinder and said measurement device (22, 24), said working cylinder
being a pneumatic working cylinder, and
said control device permits (16) replacement of the hydraulic cylinder
with a new hydraulic cylinder to be tested while said measurement device (22,
24) determines fluid quality is one of said sides of the first hydraulic

cylinder.
14. A device as claimed in claim 11 wherein the fluid device is a first

hydraulic
cylinder having a piston side and a rod side forming the fluid spaces,
respectively; and
said control device permits replacement of the first hydraulic cylinder with
a new cylinder to be tested while said measurement device determines fluid
quality in the first hydraulic cylinder.
15. A device as claimed in claim 1 wherein each said storage device comprises
working cylinder having a piston rod with a through fluid conducting passage
discharging on one side into a piston space of the respective working cylinder
and on another side into a connecting line blocked by said control device.
16. A device as claimed in claim 15 wherein said control device comprises
switching valves located in and clearing and blocking said feed lines and
connecting lines; and
said control device is connected to monitoring devices operatively coupled
to said storage devices to receive output signals from said monitoring devices

to
actuate said switch valves in respect to said output signals.
17. A device as claimed in claim 16 wherein a pressure control valve is
connected to each said feed line between the respective storage device and the
respective switching valve of said control device.
18. A device for testing at least one quality parameter of a fluid in a fluid
device at least periodically receiving a specified volume of fluid into at

least one
fluid space, comprising:
first and second storage devices receiving and storing volumes of the fluid
from the fluid device via feed lines;
a control device in fluid communication with said storage devices
controlling flow of the fluid from the fluid device to said storage devices;

and
first and second measurement devices in fluid communication via
discharge lines with said down stream of said first and second storage devices,
respectively, capable of determining a quality parameter of the fluid.
19. A device as claimed in claim 18 wherein each said storage device has a
monitoring device operatively coupled thereto indicating end positions of a

piston
movable within each said storage device.
20. A device as claimed in claim 18 wherein an actuator comprising one of the
group consisting of an electrically and/or hydraulically operated supply source
and a compressed gas source is connected to a rod side of each said storage
device.
21. A device as claimed in claim 18 wherein each said storage device
comprises a pneumatic cylinder.
22. A device as claimed in claim 18 wherein the fluid device comprises one of
the group consisting of working cylinders, hydraulic accumulators, valves,

filter
housings and flexible pressure tubing.
23. A device as claimed in claim 18 wherein said measurement devices
determine at least one of particle size, particle number, particle speed and
particle type present in the fluid, and of viscosity, aging, temperature, pH

value
and electric conductivity of the fluid.
24. A device as claimed in claim 23 wherein the fluid device is a first

hydraulic
cylinder having a piston side and a rod side connectable to said storage

devices
and said measurement devices, said storage devices being pneumatic working
cylinders; and
said control device permits replacement of the first hydraulic cylinder with
a new hydraulic cylinder with a new hydraulic cylinder to be tested while said
measurement devices determine fluid quality in said sides of the first

hydraulic
cylinder.
25. A device for testing at least one quality parameter of a fluid in a fluid
device at least periodically receiving a specified volume of fluid into at

least one
fluid space, comprising:
a storage device receiving and storing a volume of the fluid from the fluid
device via a feed line;
a control device in said feed line in fluid communication with said storage
device controlling flow of the fluid from the fluid device to said storage

device;
and
a measurement device in fluid communication via a discharge line with
and downstream of said storage device capable of determining a quality
parameter being at least one of particle size, particle number, particle speed

and
particle type in the fluid, and of viscosity, aging, temperature pH value and
electric conductivity of the fluid.
26. A device as claimed in claim 25 wherein a monitoring device operatively
coupled to storage device indicates end positions of a piston movably mounted

in
said storage device.
27. A device as claimed in claim 25 wherein an actuator comprising one of the
group consisting of an electrically and/or hydraulically operated supply source
and a compressed gas source is connected to a rod side of said storage device.
28. A device as claimed in claim 25 wherein said storage device comprises a
pneumatic cylinder.
29. A device as claimed in claim 25 wherein said storage device comprises a
working cylinder having a piston rod with a through fluid conducting passage
discharging on one side into a piston space of said working cylinder and on
another side into a connecting line blocked by said control device.
30. A device as claimed in claim 29 wherein said control device comprises
switching valves located in and clearing and blocking said feed line and said
connecting line; and
said control device is connected to a monitoring device operatively
coupled to said storage device to receive output signals from said monitoring
device and to actuate said switch valves in response to said output signals.
31. A device as claimed in claim 30 wherein a pressure control valve is
connected to said feed line between said working cylinder and the respective
switching valve of said control device.
32. A device as claimed in claim 25 wherein a second storage device and a
second measurement device are in fluid communication with a second fluid space
of the fluid device via another feed line.
33. A device as claimed in claim 25 wherein the fluid device is a first

hydraulic
cylinder having a piston side and a rod side connectable to said storage device
and said measurement device, said storage device being a pneumatic working
cylinder; and
said control device permits replacement of the first hydraulic cylinder with
a new hydraulic cylinder to be tested while said measurement device determines
fluid quality in one of said sides of the first hydraulic cylinder.

A device tests at least one quality parameter of a fluid in fluid apparatuses, e.g.,
working cylinders (10), hydraulic accumulators, valves, filter housing, pressure
tubes, which at least temporarily accommodates given fluid volume in at least
one fluid chamber (12,14). The fluid volume is stored in a storage unit (16) with
the aid of a control mechanism (16) after being discharged from the fluid
apparatus in order to be redirected from there into a measuring element (22, 24)
to verify the respective quality parameter of the fluid. The inventive device
makes is possible to specifically obtain a statement about the operability of the
respective fluid apparatus within a very short period of time.